Hindered phenolic norbornane-2,3-dicarboximides

ABSTRACT

Compounds having the formula   WHEREIN R1 and R2 are lower alkyl, R3 is alkyl, another hindered phenolic norbornane-2,3dicarboximide group, or a group -(CH2)-CO2R4 and M IS 0 TO 3, N IS 1 OR 2 AND R4 is alkyl, ARE GOOD OXIDATIVE AND THERMAL STABILIZERS OF SYNTHETIC POLYMERS.

United States Patent [1 1 Stephen HINDERED PHENOLIC NORBORNANE-Z,3-DICARBOXIMIDES [75] Inventor: John F. Stephen, New City, NY.

[73] Assignee: Ciba-Geigy Corporation, Ardsley,

22 Filed: Dec. 28, 1973 21 Appl. No.: 429,234

[52] US. Cl... 260/326 C; 260/45.8 N; 260/45.8 SN

Primary ExaminerJoseph A. Narcavage Attorney, Agent, or FirmNestor W. Shust [57] ABSTRACT Compounds having the formula July 22, 1975 (Cl- 1 G OH wherein R and R are lower alkyl, R is alkyl, another hindered phenolic norb0rnane-2,3-dicarboximide group, or a group --(Cl**l )--CO R and l m is 0 to 3,

n is l or 2 and R is alkyl,

are good oxidative and thermal stabilizers of synthetic polymers.

11 Claims, No Drawings HINDERED PHENOLIC NORBORNANE-2,3-DICARBOXIMIDES DETAILED DISCLOSURE This invention relates to hindered phenolic norbornane-Z,3-dicarboximides and organic compositions stabilized therewith. More specifically, these compounds are useful as stabilizers or organic materials which are subject to oxidative and thermal degradation. The compounds of this invention can be represented by the formula (CH 2 s R N(CH2)"TQ-OH 2 o vR I wherein n R and R are the same or different (lower) alkyl groups of l to 4 carbon atoms, m has a value of 0 to 3, n has a value of l or 2, and R is alkyl group of l to 18 carbons, a group of the where x has a value of 2 to 18,

R is alkyl group of l to 18 and p has a value of] to 2. v

The R and R groups can be any straight or branched chain alkyl having l to 4 carbon atoms, such as methyl, ethyl, isopropyl, n-butyl and tert-butyl. Preferably these groups are methyl, iso propyl and tert-butyl groups. Most preferably both groups are tert-butyl. The integer n is preferably 1.

The R group can be any alkyl, that is, methyl, ethyl, propyl, butyl, hexyl, octyl and the like up to 18 carbons, but preferably it is from 4 to 18 carbons. In the preferred embodiment R can be also a group of formulae ll, Ill and IV where R and R are preferably methyl, isopropyl or tert-butyl and especially tert-butyl and x has a value of 2 to l8 and especially 2 to 6. R can also be preferably a group (Cl-l ),,CO R where R is alkyl from 4 to 18 carbons.

wherein R and R are as defined previously, with the appropriate exo-S-alkylthionorbornane-endo-2,3- dicarboxylic anhydride in a suitable solvent such as toluene at reflux temperatures. Exo-S- alkylthionorbornane-endo-Z,3-dicarboxylic anhydrides can be prepared from 5-norbornene-endo-2,3- dicarboxylic anhydride and an appropriate mercaptan in the presence of a suitable initiator such as azobisisobutyronitrile in a solvent such as dioxane. 5- Norbornene-endo-2,3-dicarboxylic anhydride is commercially available.

The 3,5-dialkyl-4-hydroxyphenylsubstituted amines wherein m is O can be prepared as described in U.S. Pat. No. 3,198,797. The amine, when m is 2 can be prepared, for example, through chloromethylation of a dialkylphenol as described in U.S. Pat. No. 2,838,57l, followed by treatment of the resulting chloromethyl derivative with sodium or potassium cyanide and reduction of the resultant dialkylhydroxyphenylacetonitrile to the amine. The amine wherein m is 3 can be prepared by reducing the appropriate 3-(3,5-dialkyl-4- hydroxyphenyl)-propionitrile with lithium aluminum hydride to yield the corresponding amine. The nitrile can be prepared according to the method described in U.S. Pat. No. 3,121,732 wherein the appropriate dialkylphenol is reacted with acrylonitrile.

The compounds of formula I wherein m is 0, 2 and 3 can also be prepared by free radical addition of an appropriate mercaptan of an imide of the formula O R Amy) on wherein R and R are as defined previously and R is an alkyl group such as methyl or ethyl, with the appropriate exo-S-alkylthionorbornane-endo-2,3- dicarboximide in a suitable solvent such as N,N-dimethylformamide. The 3,5-dialkyl-4-hydroxybenzyldialkyl amines can be prepared as described by E. P. Previc et al., Industrial and Engineering Chemistry, 53, 469 (1961).

Exo--alkylthionorbornane-endo-2,3-dicarboximides can be prepared by free radical addition of the appropriate mercaptan to 5-norbornene-endo-2,3- dicarboximide in the presence of an initiator such as azobisisobutyronitrile and a solvent such as dioxane.

5-Norbornene-endo-2,3-dicarboximide can be prepared from 5-norbornene-endo-2,3-dicarboxylic anhydride by the procedure described by W. S. Worrall in J. Amer. Chem. Soc. 82,5707 (1960).

The compounds of formula I wherein m is l and R is (CH ),,CO R" can also be prepared by csterifying the appropriate N-(3,5-di-tert-butyl-4-hydroxybenzyl)- exo-5-( 2-carboxyethylthio)-norbornane-endo-2,3- dicarboximide and N-(3,5-di-tert-butyl-4- hydroxybenzyl)-exo-5-carboxymethylthionorbornaneendo-2,3-dicarboximide with an alcohol in the presence of a suitable catalyst such as p-toluenesulfonic acid. The above acids can be prepared by hydroxybenzylating the corresponding exo-5-(2-carboxyethylthio)- norbornane-endo-2,3-dicarboximide and exo-5- carboxymethylthionorbornane-endo-2,3- dicarboximide with the appropriate 3,5-dialkyl-4- hydroxybenzyldialkyl amine of the formula IV. Exo-S- (2-carboxyethylthio )-norbornaneendo-2,3- dicarboximide and carboxymethylthionorbornane-endo-2,3 dicarboximide can be prepared by free radical addition of 3-mercaptopropionic and mercaptoacetic acid, respectively, to 5-norbornene-endo-2,3-dicarboximide in the presence of an initiator such as azobisisobutyronitrile in a solvent such as dioxane.

The following examples further illustrate the preparation of the compounds without introducing any limi-' tations.

exo-5- EXAMPLE 1 Exo-5-( Z-carboxyethylthio)-norbornane-endo-2,3- dicarboximide In a nitrogen atmosphere, 3-mercaptopropionic acid (1 1.7 g, 0.1 1 mole) was added to a stirred solution of 5-norbornene-endo-2,3-dicarboximide 16.3, 0.1 mole) in 100 ml of dioxane. The temperature rose from 25 to 38. The mixture was then heated at 6570 and a solution of azobisisobutyronitrile (1.6 g) in 40 ml of dioxane was added over a period of 1.5 hours. After the addition was completed the mixture was heated at 6570 for hours. The dioxane was evaporated under reducedpressure and the residue thus obtained was recrystallized from ethanol to give 17.4 g (65%) of the title compound, m.p. l87189.

EXAMPLE 2 N-( 3 ,5-di-tert-butyl-4-hydroxybenzyl )-exo-5-( 2- carboxyethylthio)-norbornane-endo-2,3-

dicarboximide In a nitrogen atmosphere, a stirred-mixture 0f the above imide (16.2 g, 0.06 mole) and 2,6-di-t-butyl-4- dimethylaminomethylphenol (17.4 g, 0.666 mole) in 100 ml of N,N-dimethylformamide was heated at 110-l20 for 21 hours. The mixture was poured into water and the oily product was extracted with ether. The ether extract was washed with dilute hydrochloric acid and water. After drying over Na- SO. the ether solution was evaporated to yield a solid residue. After trituration with petroleum ether the solid of 21.0 g was recrystallized from ethanol-water to give 19.1 g (65%) of hydroxybenzylated imide, m.p. l64l66.

EXAMPLE 3 N-( 3 ,5-di-tert-butyl-4-hydroxybenzyl )-exo-5-( 2-carbon-dodecyloxyethylthio)-norbornane-endo-2,3- I

dicarboximide A stirred mixture of the product of Example 2 (10.7 g, 0.0224 mole), dodecyl alcohol (4.1 g, 0.022 mole) and p-toluenesulforiic acid (100 mg.) in ml of toluene was refluxed for 36 hours, water being removed with a Dean-Stark trap. The toluene was evaporated under reduced pressure, and the residual oil thus obtained was dissolved in ether. The ether solution was washed with aqueous sodium carbonate and water. Evaporation of the dried (NaySOflether solution gave 11.5 g (88%) of the desired ester as an oil which was heated at /0.05 mm for 12 hours prior to analysis:

Anal. Calcd. for C H NO S: C, 71.41; H, 9.37; N, 2.13. Found: c,71.'s1; 11, 9.42; N, 2.08.

EXAMPLE 4 Exo-S-n-Octadecylthionorbornane-endo-2,3- dicarboxylic anhydride In a nitrogen atmosphere a stirred. mixture of 5- norbornene-endd-Z,3-dicarboxylic anhydride (16.3 g, 0.1 mole) and n-octadecyl' mercaptan (30 g, 0.105 mole) in ml of dioxane containing 0.2 g of azobisisobutyronitrile was heated at 7075 for 18 hours. Upon cooling, heptane was added and the precipitated solid was filtered off and was recrystallized from methanol to give 28.1 g (62.5%) of the title anhydride, m.p.

I EXAMPLES N-( 3 ,5-di-tert*butyl-4-hydroxypheny1)-exo-5-noctadecylthionorbornane-endo-2,3-dicarboximide EXAMPLE 6 exo-5-n-Dodecylthionorbornane-endo-2,3- dicarboxylic anhydride ln a nitrogen atmosphere a stirred mixture of 5 -n0rbornene-endo-2,3-dicarboxylic anhydride (24.6 g, 0.15 mole) and lauryl mercaptan (31.8 g, 0.157 mole) in m1 of dioxane containing 0.2 g of azobisisobutyronitrile was heated at 6070 for 20 hours. The sol- .vent and excess mercaptan were evaporated under reduced pressure and the oily residue thus obtained was crystallized from petroleum ether to give 27.0 g (49.0%) of exo-5-n-dodecylthionorbornane-endo-2,3- dicarboxylic anhydride, m.p. 6971.

EXAMPLE 7 N-( 3,5-di-tert-buty1-4-hydroxyphenethyl )-exo-5-ndodecylthionorbornane-endo-2,3-dicarboximide EXAMPLE 8 N-( 3 ,5-di-tert-butyl-4-hydroxyphenylpropy1)-exo-5-ndodecylthionorbornane-endo-Z,3dicarboximide In a nitrogen atmosphere a stirred solution of exo-5- n-dodecylthionorbornane-endo-2,3-dicarboxylic anhydride (9.16 g, 0.025 mole) and 3,5-di-tert-butyl-4- hydroxyphenylpropyl amine (6.58 g, 0.025 mole) in 100 ml toluene was heated at 80-85 for 1 hour. p-Toluenesulfonic acid (0.05 g) was added and the mixture was heated under reflux for 5 hours, water being removed with a Dean-Stark trap. The toluene was evaporated in vacuo to give 12.5 g of a solid residue. Recrystallization from methanol gave 10.9 g (71%) of the title imide, m.p. 8284.

EXAMPLE 9 N( 3 ,5-di-tert-butyl-4-hydroxyphenyl )-exo-5-ndodecylthionorbornane-endo-2,3-dicarboximide In a nitrogen atmosphere a stirred solution of N-(3,5- di-tert-butyl-4-hydroxyphenyl)-5-norbornene-endo- 2,3-dicarboximide (3.61 g, 0.098 mole) and lauryl mercaptan (21.3 g, 0.105 mole) in 100 ml of dioxane containing azobisisobutyronitrile (1.6 g, 0.01 mole) was heated at 7580 for 3 hours. The dioxane was evaporated under reduced pressure and the resulting oil was crystallized twice from aqueous methanol to give 28.0 g (50.0%) of N-(3,5-di-tert-butyl-4-hydroxyphenyl)- exo-5-n-dodecylthionorbornane-endo-2,3- dicarboximide, m.p. 6870.

EXAMPLE 10 exo-5-n-Dodecylthionorbornane-endo-2,3- dicarboximide In a nitrogen atmosphere a stirred mixture of 5- norbornene-endo-2,3-dicarboximide (24.6 g, 0.15 mole) and lauryl mercaptan (33.3 g, 0.165 mole) in 150 ml of dioxane was heated to 65 when a solution of azobisisobutyronitrile (0.25 g) in 5 ml of dioxane was added. The mixture was then heated at 65 for 18 hours. The dioxane was evaporated in vacuo and the residue was recrystallized from heptane and then methanol to give 33.0 g (60%) of exo-5-ndodecylthionorbornane'endo-Z,3-dicarboximide, m.p. 1l3-115.

EXAMPLE 1 1 N-( 3,5-di-tert-buty1-4-hydroxybenzyl)-exo-5-nclodecylthionorbornane-endo-2,3-dicarboximide In a nitrogen atmosphere, a stirred mixture of exo-5- n-dodecylthionorbornane-endo-2,3-dicarboximide (10.8 g, 0.03 mole) and 2,6-ditert-butyl-4- dimethylaminomethylpheno] (8.3 g, 0.0315 rnole) in ml of N,N-dimethylformamide was heated at -125 for 4 hours. The cold mixture was poured into water and the oil .which separated was extracted with ether. The ether extract was washed with dilute hydrochloric acid and then water. The dried (Na SO solution was evaporated under reduced pressure to give 15.8 g of a viscous oil. Chromatography over silica gel using heptane as solvent gave 7.6 g of pure title com pound as a viscous oil.

Anal. Calcd. for C H NO S: C, 74.05; H, 9.84; N, 2.40. Found: C, 74.33; H, 9.92; N, 2.35.

Following the above procedure except-for employing 2,6-dimethyl-4-dimethylaminomethyl there is obtained N-(3,5-dimethyl-4-hydroxyphenyl)-exo-5-(2-carbo-ndodecyloxyethylthio)-norbornane-endo-2,3- dicarboximide.

EXAMPLE 12 exo-5-( 2-carbo-n-dodecyloxyethylthio )-norbornaneendo-2,3-dicarboxylic anhydride In a nitrogen atmosphere a stirred mixture of 5- norbornene-endo-Z,3-dicarboxylic anhydride (16.4 g, 0.1 mole) and n-dodecy1-3-mercaptopropionate (29.4 g, 0.105 mole) in ml of dioxane containing 0.2 g of azobisisobutyronitrile was heated at 65-70 for 18 hours. The dioxane was evaporated under reduced pressure to give an oily residue which was dissolved in hexane. The hexane solution was filtered to remove insoluble material and the filtrate was evaporated to give 43.0 g (98 percent) of the desired anhydride, m.p. 4447.

EXAMPLE l3 N-(3,5-di-tert-butyl-4-hydroxyphenyl)-exo-5-(2-carbon-dodecyloxyethylthio )-norbornane-endo-2,3-

dicarboximide Under nitrogen, a stirred solution of the above anhydride (1 1.0 g, 0.025 mole) and 2,6-di-tert-butyl-4- aminophenol (5.55 g, 0.025 mole) in 150 ml of dry tol' uene was heated at 90 for 30 minutes and then under reflux for 5 hours, water being removed with a Dean- Stark trap. The toluene was evaporated under reduced pressure and the oily residue was purified by dry column chromatography on silica gel using chloroform as solvent. In this way there was obtained 4.8 g (30.0%) of pure esterimide as an oil.

Anal. Calcd. for C I-I NO S: C, 71.10; H, 9.27; N, 2.18; S, 4.99. Found: C, 71.40; H, 8.98; N, 2.25; S, 4.65.

Employing the above procedure except for employing 2,6-diisopropyl-4-aminophenol and 2-methyl-6- tert-butyl-4-aminophenol, there are obtained N-(3,5- diisopropyl-4-hydroxypheny1)-exo-5-(2-carbo-ndodecyloxyethylthio) norbornane endo 2,3- dicarboximide and N-( 3-methyl S-tert-butyl-4- hydroxyphenyl)-exo-5-( 2-carbo-ndodecyloxyethylthio)-norbornane-endo-2,3- dicarboximide. i

Compounds reported in Table I were prepared according to the procedures described above.

Each compound that was an oil was purified hy Chromatography over silica gelv The microanalytical results for hydrogen. carbon and nitrogen corresponded to th calculated values. 7 "-Y has the structure TABLE II Light Stabilization of Polypropylene Time to 0.5 Carbonyl Stabilizcr* Absorbance Units 1. 0.2% Compound of Ex. 9 1170 hours 2. 0.2% Compound of Ex. I105 hours 3. 0.2% Compound of Ex. 11 1100 hours 4. 0.2% Compound of Ex. 16 945 hours 5. 0.2% Compound of Ex. 17 950 hours 6. 0.2% Compound of Ex. 18 790 hours 7. 0.2% Compound of Ex. 19 945 hours 8. 0.2% Compound of Ex. 3 I090 hours 9. 0.2% Compound of Ex. 20 795 hours 10. 0.2% Compound of Ex. [3 790 hours II. 0.2% Compound of Ex. 2l 730 hours l2. 0.2% Compound of Ex. 22 740 hours l3v No stabilizers -I7O hours The composition also contains 05% of UV absorber 2( 2'-hydroxy-3 .5-di-turt-butylphenyl )-5-chlorobenzotriazole.

The compositions of Table II are equally stabilized when 2 2-hydroxy-3,5'-di-t-butylphenyl -5- chlorobenzotriazole is replaced with the following UV absorbers:

a. 2-hydroxy-4-methoxy-5-sulfobenzophenone trihydrate b. 2-hydroxy-4-n-octoxybenzophenone c. 2,2thiobis(4-t-octylphenolate) -n-butylamine nickel II d. p-octylphenyl salicylate e. 2,2'-dihydroxy-4,4'-dimethoxybenzophenone f. 2 2'-hydroxy-5'-methylphenyl -benzotriazole Other hindered phenolic antioxidants may be used in place of di-octadecyl(3-5-di-t-butyl-4-hydroxybenzyl) phosphate in the above mentioned compositions for example di-n-octadecyl a-(3-t-butyl-4-hydroxy 4- methylbenzyl) malonate, 2,4bis(n-octylthio)-6-(3,5- di-t-butyl-4-hydroxyaniline)-1,3,5-triazine, octadecyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate; penthydroxypheny'l )isocyanurate,

EXAMPLE l5 Unstabilized polypropylene powder (Hercules Profax 6501) was thoroughly blended with the stabilizers indicated in Table III below. The blended materials were then milled'on a two-roll mill at 182 C for l0 minutes, after which time the stabilized polypropylene was sheeted from the mill and allowed to cool.

The milled polypropylene sheets were then cut into pieces and pressed for 7 minutes on a hydraulic press at 218 C, 2,000 pounds per square inch pressure. The resulting plaques of 25 mil thickness were tested for resistance to accelerated aging in a forced draft oven at l50 C. When the plaques showed the first signs of decomposition (e.g., cracking or brown edges) they were considered to have failed. The results were as follows:

TABLE III Oven Aging of Polypropylene Time to Failure in Hours I Formulations Stabilizer A 2 C 1. Compound of Ex. 9 260 270 305 2. Compound of Ex. 5 415 425 375 3. Compound of Ex. II 280 265 530 4. Compound of Ex. I6 365- 405 380 5. Compound of Ex. 17 270 I 950 6. Compound of Ex. 18 50 50 715 7. Compound of Ex. 19 65 65 I85 8. Compound of Ex. 3 280 243 875- 9. Compound of Ex. 20 200 420 10. Compound of Ex. 13 545 420 655 ll. Compound of Ex. 21 450 425 545 12. Compound of Ex. 22 465 530 580 13. No stabilizer -3 Formulation A contains 0.2% of the indicated stabilizer of this invention. "Formulation B contains 0.2% of the indicated stabilizer and 0.5% of UV absorber 2(2-hydroxy-3,5-diterthutylphenyl)-5-chlorobenzotriazole.

Formulation C Contains 01% of the indicated stabilizer and 0.3% of dilaurylthiodipropionate,

What is claimed is: 1,. A compound of the formula R and R are thesame or different (lower)alkyl groups of l to 4 carbon atoms,

m has a value of O to 3,

n has a value of l or 2, and

R is alkyl group of l to 18 carbons, a group of the formulae x has a value of2 to 18,

R is alkyl of 1 to 18 carbons, and

2 has a value of l to 2.

2. Compounds of claim 1 wherein R and R are methyl, isopropyl or tert-butyl, n is I, R is alkyl from 4 to 18 carbons or a group of formulae II, III or IV where x is 2 to 6 and R is alkyl having from 4 to 18 carbons.

3. Compounds of claim 2 wherein R and R are tertbutyl groups.

4. The compound of claim 1 which is N-(3,5-di-tertbutyl-4-hydroxyphenyl)-exo-5-noctadecylthionorbornane-end0-2,3-dicarboximide.

5. The compound of claim 1 which is N-(3,5-di-tertbutyl-4-hydroxyphenyl)-exo-5-ndodecylthionorbornane-endo-Z,3-dicarboximide.

6. The compound of claim 1 which is N-(3,5-di-tertbutyl-4-hydroxyphenyl)-exo-5-(2-carbo-n-dodecyloxyethylthio)-norbornane-endo-2,3-dicarboximide.

7. The compound of claim 1 which is N-(3,5-di-tertbutyl-4-hydroxybenzyl)-exo-5-noctadecylthionorbornane-end0-2,3-dicarboximide.

8. The compound of claim 1 which is trimethylenedithio-bis [N-(3,5di-tert-butyl-4- hydroxybenzyl)-5-norbornane-end0-2,3- dicarboximide].

9. The compound of claim 1 which is 5,5 '-bis[N-(3.5- di-tert-butyl-4-hydroxybenzyl)-norbornane-endo-2,3- dicarboximide1sulfide.

10. The compound of claim 1 which is N-( 3,5-di-tertbutyl-4-hydroxybenzyl)-exo-5-(2-carbo-ndodecyloxymethylthio)-norbornane-endo-2,3- dicarboximide.

11. The compound of claim 1 which is N-(3,5'di-tertbutyl-4-hydroxybenzyl-exo-5-(2-carbo-noctadecyloxymethylthio)-norbornane-endo-2,3-

dicarboximidei 

1. A COMPOUND OF THE FORMULA
 2. Compounds of claim 1 wherein R1 and R2 are methyl, isopropyl or tert-butyl, n is 1, R3 is alkyl from 4 to 18 carbons or a group of formulae II, III or IV where x is 2 to 6 and R4 is alkyl having from 4 to 18 carbons.
 3. Compounds of claim 2 wherein R1 and R2 are tert-butyl groups.
 4. The compound of claim 1 which is N-(3,5-di-tert-butyl-4-hydroxyphenyl)-exo-5-n-octadecylthionorbornane-endo -2,3-dicarboximide.
 5. The compound of claim 1 which is N-(3,5-di-tert-butyl-4-hydroxyphenyl)-exo-5-n-dodecylthionorbornane-endo-2,3-dicarboximide.
 6. The compound of claim 1 which is N-(3,5-di-tert-butyl-4-hydroxyphenyl)-exo-5-(2-carbo-n-dodecyl-oxyethylthio)-norbornane-endo-2,3-dicarboximide.
 7. The compound of claim 1 which is N-(3,5-di-tert-butyl-4-hydroxybenzyl)-exo-5-n-octadecylthionorbornane-endo -2,3-dicarboximide.
 8. The compound of claim 1 which is trimethylenedithio-bis (N-(3,5-di-tert-butyl-4-hydroxybenzyl)-5-norbornane-endo-2,3-dicarboximide).
 9. The compound of claim 1 which is 5,5''-bis(N-(3,5-di-tert-butyl-4-hydroxybenzyl)-norbornane-endo-2,3 -dicarboximide)sulfide.
 10. The compound of claim 1 which is N-(3,5-di-tert-butyl-4-hydroxybenzyl)-exo-5-(2-carbo-n-dodecyloxymethylthio)-norbornane-endo-2,3-dicarboximide.
 11. The compound of claim 1 which is N-(3,5-di-tert-butyl-4-hydroxybenzyl-exo-5-(2-carbo-n -octadecyloxymethylthio)-norbornane-endo-2,3-dicarboximide. 